Drilling-bit.



N. 1. Mc KE NZ|E.

DRILLING BIT.

APPLICATION FILED 001115. I917- 1,277,970. PatentedSept. 3,1918.

2 SHEETSSHEET I.

N. J. MCKENZIE. DRILLING BI T APPLICATION FILED OCT. I5. 1917- 1,277,970. Patented Sept. 3, 1918.

2 SHEETS-SHEET}.

To all whom it may concern:

Be it known that I, NORMAN J. MCKENZIE a citizen of the United States, residing at Bisbee, inthe county of Cochise and State of Arizona, have invented new and useful specification.

. certaln improvements in bits which will enable them to perform the required work with a minimum expenditure of power and a minimum degree of resistance to the cutting teeth.

In the accompanying drawings, Figure 1 a side elevation of one form of bit; Fi 2 is a side 'elevation'of a further mod' ed form; Fig. 3 is an end view of same; Fig. 4: w is an end rview of a modified form; Fig. 5 is a side elevation of a further modification; I Fig. 6 is an end view of same; and Figs. 7, o 8, 9 and 10 are end views of other modified patterns of my invention involving like particulars 'of construction and operation.

Like characters of reference designate corresponding parts throughout the several views.

Referring to the accompanying drawings, 1 indicates the shank of the drill, which may be of any suitable shape or size; suitable ribs 2 are provided at the working end or, face of the drill, preferably diverging outwardly as illustrated in Figs. 1, 2, 5.

The face of the drill is provided with a a plurality of novel inversely curved cutting teeth 5, which are se arated by grooves 6. These grooves provi e a channel opening into the flutings 7 which extend upwardly and longitudinally from the face of the drill and provide a passage for chips and dust produced by the drilling. Each rib is pro vided with a clearance groove or cavity 4 opening into the longitudinal fiutings 9 which are similar in shape and function to fiutings 6 and 7 I may provide one or more center teeth 11 inthe face ofthe drill. These center teeth are relatively smalland may be of any suitable form, such as illustrated Q inthe drawings. Their usefulness consistsin their cofiperation with the inversely curved Specification of Letters Patent.

Drilling-Bits, of which the following is a] The object of my invention is to provide' 'tudinal flutings into NORMAN J. MGKENZIE, 0F BISBEE, ARIZONA.

DRILLING-BIT.

Patented Sept. 3, 1918.

Application filed October 15, 1917. Serial No. 196,6.

teeth in fracturing rock that is especially hard. I preferably provide the drills with one or more suitable channels 10, so that water may be supplied through the drill to lessen the danger of the bore becoming choked. While several patterns of my invention are illustrated, yet it will be observed that in each. instance I require inversely curved teeth forcutting; grooves and cavities opening out of the face of the drill, and longiwhich these grooves open to allow for the escape of chips and dust; .while I may. provide center teeth, the principal work of fracturing the rock is performed by the inversely curved outer teeth, which perform a more effective cutting operation than is accomplished with the ordinary drill bit.

It is by this novel positioning and shape of teeth that I am enabled to relieve the resistance in the center of the drill bit, and to increase the drill efiiciency toward the outer edge of the bore, which relieves the corners of the bit while in operation. The outer portions of the inversely curved teeth strike approximately ter portions, in the instance of the forms having relatively lar e inversely curved teeth; and, similarly t these inversely curved teeth operate at ap proximately right angles to the relatively small center teeth, shown forms.

My drill bits are intended for general use in mining drilling and boring, and it is my object to uniformly increase the fracturing efliciency from the center to the periphery of the face of the drill. This peculiar form of cutting teeth has proven more eflicient than any radially arranged cutting teeth, and overcomes the defect which many drills have of providing a disproportionate amount of cutting surface at the center, as compared with the outer portions of the face of the drill.

'This is particularly .important in-view of the necesslty for effectually ejecting cuttin from under the central portion of the dri I,

e outer portions of in the modified 1s at right angles to their cennevmve and the grooves and fiutings intervening heclearance grooves there'between, longituditWeen the inversely curved cutting teeth pmnel fiutings extending up the sides of the vide an eificient passage fer chips. drill and communicating with the clearance What 1 claim is: grooves in the face of the drill, the inversely In drill hits, the combination of teeth pecurved teeth having concave outer faces for sitiened near the center of the ill, a pluthe ejection of chips and (lust, substantially relity 0f inversely curved outer teeth spaced, as end for the purposes described, .fijom the first mentioneel teeth and heving NURMAN J. MGKENZIE. 

